Hydrogen‐Bonding Catalyzed Ring‐Closing C−O/C−O Metathesis of Aliphatic Ethers over Ionic Liquid under Metal‐Free Conditions
作者:Huan Wang、Yanfei Zhao、Fengtao Zhang、Yunyan Wu、Ruipeng Li、Junfeng Xiang、Zhenpeng Wang、Buxing Han、Zhimin Liu
DOI:10.1002/anie.202004002
日期:2020.7.13
have wide applications, and their efficient and green synthesis is very interesting. Herein, we report hydrogen‐bonding catalyzed ring‐closing metathesis of aliphatic ethers to O‐heterocycles over ionic liquid (IL) catalyst under metal‐ and solvent‐free conditions. The IL 1‐butylsulfonate‐3‐methylimidazolium trifluoromethanesulfonate ([SO3H‐BMIm][OTf]) is discovered to show outstanding performance, better
杂环具有广泛的应用,其高效和绿色合成非常有趣。在此,我们报道了在无金属和无溶剂条件下,离子液体(IL)催化剂上脂族醚与O杂环的氢键催化开环复分解反应。发现IL 1-丁基磺酸盐-3-甲基咪唑鎓三氟甲磺酸盐([SO 3 H-BMIm] [OTf])具有优异的性能,优于报道的催化剂。由于产物与IL催化剂之间的不混溶性,界面效应在介导反应速率中起重要作用,并且产物可以自发分离。NMR分析和DFT计算表明,[SO 3H-BMIm] [OTf]可以与一个醚分子形成三个强H-键,它们通过环状氧鎓中间体催化醚的转化。可以从它们相应的醚中以优异的收率(例如,> 99%)获得一系列包括四氢呋喃,四氢吡喃,吗啉和二恶烷的O-杂环。这项工作为从脂肪族醚生产O杂环开辟了一种高效且无金属的方式。